Diagram 4 - Isolator Input a - Engine (‑) negative terminal b - Meter extension lead c - Isolator input Diagram 5 - Isolator Output 1 a - Engine (‑) negative terminal b - Meter extension lead c - Isolator output 1 73103 a A m A C O M V H z mV V H z TEMPm A A IG OFF IP H z TEMP b c a A m A C O M V H z mV V H z TEMPm A A IG OFF IP H z TEMP b c 73228 Charging and Starting System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6B-15
Diagram 6 - Isolator Output 2 a - Engine (‑) negative terminal b - Meter extension lead c - Isolator output 2 Alternator Test Data Examples IMPORTANT: Voltage should increase in direction of arrows Voltage Increase Voltage Engine + Alternator Output Isolator Input Isolator Out 1 Isolator Out 2 Isolator Out 3 Key Off, Engine Off Fuse check (non‑isolator) 0 State of charge Fuse check State of charge Fuse check State of charge Fuse check Key On, Engine Off 0 Engine On, Idle Engine On, 2000 RPM Good Alternator Voltage Engine (+) Alternator Output Isolator Input Isolator Out 1 Isolator Out 2 Isolator Out 3 Key Off, Engine Off 12.55 0 0 12.56 12.30 12.50 Key On, Engine Off 12.43 0 0 12.45 12.30 12.50 Engine On, Idle 13.81 14.45 14.44 13.82 13.80 13.81 Engine On, 2000 RPM 14.50 15.24 15.20 14.50 14.50 14.50 Bad Alternator Voltage Engine (+) Alternator Output Isolator Input Isolator Out 1 Isolator Out 2 Isolator Out 3 Key Off, Engine Off 12.55 0 0 12.56 12.30 12.50 Key On, Engine Off 12.43 0 0 12.45 12.30 12.50 Engine On, Idle 12.13 0 0 12.15 12.30 12.50 Engine On, 2000 RPM 12.02 0 0 12.03 12.30 12.30 73229 a A m A C O M V H z mV V H z TEMPm A A IG OFF IP H z TEMP b c Charging and Starting System Page 6B-16 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Test Data Sheet Dealer Contact Information Dealer number: Phone number: Contact name: • Hull ID number ______________________ • Boat make and model ________________ • Engine serial number_________________ • Engine position, i.e. single, port, starboard______________________ Record Test Results Here Voltage Battery (+) Engine (+) Alternator Output Boats without isolator/s Alternator Output Boats with isolator/s Isolator Input Isolator Output 1 (to cranking battery) Isolator Output 2 (if equipped) Key Off, Engine Off Key On, Engine Off N/A Engine On, Idle N/A Engine On, 1000–2000 RPM N/A Charging and Starting System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6B-17
Starting System Starting System Components and Connections ‑ DTS a - Propulsion control module (PCM) b - Start relay c - Main power relay (MPR) d - Fuse block ‑ 20‑amp fuse used for the start circuit e - Starter motor f - Starter solenoid g - Hot stud NOTE: RED* indicates a black cable with red sleeves at the ring terminals. h - Chassis ground stud i - 14‑pin data harness (engine to helm) j - To helm components; refer to DTS Diagnostic Manual 8M0057654 k - Clean power harness with 5‑amp fuse l - Engine starting battery m - Shift actuator RED RED YEL/PPL RED/WHT RED RED/BLU BLK/BLU YEL/RED RED/WHT RED/BLU BLK/BLU YEL/PPL BLK/YEL PPL YEL BLK GRN PNK BLK/YEL PPL YEL RED/BLK BLK YEL/RED RED* RED* RED RED* RED/BLK BLK RED* BLK BLK BLK BRN WHT BLU BRN WHT BLU a b c d e f g h i j k l m 66094 Charging and Starting System Page 6B-18 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Starting System Components and Connections ‑ Mechanical Typical mechanical engine controls a - Propulsion control module (PCM) b - Start relay c - Main power relay (MPR) d - Fuse block ‑ 20‑amp fuse used for the start circuit e - Starter motor f - Starter solenoid g - Hot stud NOTE: RED* indicates a black cable with red sleeves at the ring terminals. h - Chassis ground stud i - E‑stop switch (lanyard type shown) j - Neutral start switch (typically integral to the remote control) k - Ignition key switch (typical) l - 14‑pin data harness (engine to helm) m - Clean power harness with 5‑amp fuse n - Engine starting battery o - Shift actuator YEL/RED RED RED YEL/PPL RED/WHT RED RED/BLU BLK/BLU YEL/RED RED/WHT RED/BLU BLK/BLU YEL/PPL BLK/YEL PPL YEL/RED RED BLK BLK/YEL PPL YEL/RED YEL/RED PPL/WHT YEL/RED RED BLK BLK/YEL PPL PPL/WHT GRN PNK BLK/YEL PPL YEL/RED RED/BLK BLK YEL/RED RED* RED* RED RED* RED/BLK BLK RED* YEL/RED YEL/RED RED BLK BLK/YEL PPL BLK BLK BLK BLK BLK BLK BLK/YEL BLK a b c d e f g h i j k l m n o 66091 Charging and Starting System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6B-19
Starting System Electrical Checks 1. Inspect the 20‑amp driver power fuse. a - Ignition coils ‑ 20‑amp b - Oxygen sensor ‑ 10‑amp c - Fuel pump ‑ 20‑amp d - Diagnostics ‑ 2‑amp e - Fuel injectors ‑ 20‑amp f - Advanced sound control ‑ 5‑amp (V8 only) g - Driver power (starter relay, fuel pump relay, PCM drivers) h - TVM power ‑ 15‑amp (DTS models only) i - Spare fuses (3) j - Good fuse k - Open fuse 2. Inspect the 5‑amp clean power fuse located near the engine starting battery. 3. The battery must deliver a minimum of 11 VDC to the starter. Perform a load test on the battery following the instructions supplied with the load tester. 4. Install the shunt tool to the engine harness 14‑pin connector and perform the Smart Start test in the Diagnostic screen of the CDS G3. If the starter engages, the problem lies in the hull wiring or helm harness. Refer to the preceding Starting System Components and Connections diagrams. If the starter does not engage, continue to step 5. 12‑Volt Shunt Tool 91‑889675A01 5. Inspect all connections at the battery, start relay, starter solenoid, starter motor, PCM, and the 14‑pin engine wiring harness connector for tightness and corrosion. Clean or repair as necessary. 6. Remove the start relay and socket from behind the electrical panel (press the tab to release), and remove the relay from the socket. a - Electrical panel b - Start relay socket on the engine harness c - Start relay 7. Measure the resistance of the relay's coil, between terminal 86 and terminal 85. Replace the relay, if the coil's resistance is not within specification. 67575 30 85 87 86 Four-pin relay pin identification Start Relay Coil resistance (terminal 86 to terminal 85) 80–100 Ω j i 5 20 2 10 20 20 20 a b c d e f g SPARE FUSES 15 h k 64390 a b c 66554 Charging and Starting System Page 6B-20 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
8. With the key switch in the START position, the starter drive should engage the engine flywheel. If not, turn off the key switch, and measure the resistance between the yellow/red terminal on the starter solenoid and engine ground. If resistance is not within specification, the starter solenoid is defective and must be replaced. a - Starter motor b - Starter solenoid yellow/red terminal c - Engine ground Starter Solenoid Coil resistance (yellow/red terminal to ground) 0.2–0.4 Ω 9. If the starter drive audibly engages the engine flywheel, but the starter does not rotate, remove the starter and test the no load current draw. If the current draw is not within specification, replace the starter assembly. Starter No load current draw 60–80 A Key Switch Test (Four‑Position) 1. Disconnect the key switch from the command module harness. 2. Set ohmmeter on R x 1 scale for the following tests. 3. If meter readings are other than specified in the following tests, verify that the switch and not the wiring is faulty. If the wiring checks OK, replace the switch. a - Pin A ‑ Red b - Pin B ‑ Black c - Pin C ‑ Purple/white d - Pin D ‑ Purple e - Pin E ‑ Black/yellow f - Pin F ‑ Yellow/red Key Position Continuity should be indicated at the following points: OFF B E a b c 66556 3887 c b d e f a Charging and Starting System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6B-21
Key Position Continuity should be indicated at the following points: Accessories A C RUN A D START A F F D A D Key Switch Test (Three‑Position) a - Pin A b - Pin B c - Pin C d - Pin D e - Pin E f - Pin F Ref. No. Pin Wire Color Description a A Red 12 volts b B Black Ground c, d C, D Purple RUN e E Black/yellow OFF f F Yellow/red START Meter Test Leads Key Position Reading (Ω) Red Black Pin B Pin E OFF Continuity Pin A Pin F RUN Continuity Pin A Pin C, D Pin A Pin F START Continuity Pin F Pin C, D Continuity Pin A Pin C, D Continuity c b d e f a 18868 Charging and Starting System Page 6B-22 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Electrical Systems Section 6C - Conventional Midsection (CMS) Power Trim Table of Contents Electrical System Troubleshooting.................................... 6C-2 General Checks..........................................................6C-2 Condition/Problem...................................................... 6C-2 Problem/Solution........................................................ 6C-2 Power Trim Electrical Circuit...................................... 6C-2 Troubleshooting the Down Circuit.............................. 6C-7 Troubleshooting the Up Circuit................................... 6C-8 Troubleshooting the Down and Up Circuits (All Circuits Inoperative)................................................ 6C-9 Trim Circuit........................................................................ 6C-9 Trim Up Circuit..........................................................6C-10 Trim Down Circuit..................................................... 6C-11 Power Trim Relay Test.................................................... 6C-11 Trim Position Sensor Troubleshooting.............................6C-12 Trim Position Sensor................................................ 6C-12 Troubleshooting the Trim Position Circuit.................6C-12 Trim Position Sensor Location..................................6C-14 Testing the Trim Position Sensor Circuit with DMT 2004A....................................................................6C-14 Trim Switches and Sensor ‑ DTS.................................... 6C-15 Trim Switches and Sensor ‑ Mechanical......................... 6C-16 Conventional Midsection (CMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6C-1 6 C
Special Tools DMT 2004 Digital Multimeter 91‑892647A01 A m A C O M V H z mV V H z TEMP m A A IG OFF IP H z TEMP 4516 Measures RPM on spark ignition (SI) engines, ohms, amperes, AC and DC voltages; records maximums and minimums simultaneously, and accurately reads in high RFI environments. Electrical System Troubleshooting General Checks Before troubleshooting the power trim electrical system, check for the following: • Disconnected wires • Battery is fully charged • Battery cable connections are tight and corrosion‑free • Battery cables are secured with hex nuts, not wing nuts • Connections are tight and corrosion‑free • Plug‑in connections are fully engaged • Clean power is connected Condition/Problem Condition of Trim System Problem No. Trim motor does not run when trim button is depressed 1, 2, 4, 5, 6, 7 Trim system trims opposite of buttons 3 Cowl‑mounted trim buttons do not activate trim system 2, 4, 5, 6 Problem/Solution No. Problem Solution 1. Battery low or discharged Check the battery. 2. Open circuit in trim wiring Check for an open connection. 3. Wiring reversed in remote control, cowl switch, or trim leads Verify connections. 4. Wire harness corroded through Replace wire harness. 5. Internal motor problem (brushes, shorted armature) Check for an open connection. Test and replace the power trim motor if necessary. 6. Trim switch failure Replace the switch. 7. Relay not operating Verify relays are functioning correctly. Check voltage at the power trim bullet connectors. Power Trim Electrical Circuit IMPORTANT: Numerical callouts shown in the circuit diagrams are test points. Refer to Troubleshooting the Down Circuit or Troubleshooting the Up Circuit. Conventional Midsection (CMS) Power Trim Page 6C-2 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Conventional Midsection (CMS) Power Trim Notes: 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6C-3
Mechanical Power Trim Wiring Diagram S115 S114 S107 S112 GRN/WHT YEL LT BLU/WHT BLK RED/BLK LT BLU/WHT GRN/WHT RED/BLK PPL/BLK BLK/GRN LT BLU/WHT GRN/WHT BLK RED/BLK LT BLU/WHT LT BLU/WHT GRN/WHT GRN/WHT RED/BLK RED/BLK YEL PPL/BLK BLK/GRN LT BLU/WHT GRN/WHT RED LT BLU/WHT BLU RED RED RED RED BLU GRN GRN/WHT GRN BLK RED RED BLK BLK BLK b a c d e f g h k l m n GRN/WHT A1M4C2 A1 A3 H4 C2E3C3A4E4 A1 H4 A BH JP C B A 30 85 86 87 87a 30 85 86 87 87a H J K M C F P 86 30 87 85 87a 87 87a 86 85 30 RELAY KEY Relay Components as Viewed Separated Relay Connector 308786 85 308786 85 d e f g h i j k l m n 3 4 GRN/WHT 1 2 3 4 1 2 3 4 A BC B C AC A 1 2 3 1 2 31 3 A B A BA B 6 5 64670 K JHG FED C B A K JHG FED C B A 1 3 2 4 M A M L M L 1 4 A BC D E FG H 2 4 1 3 H A A BC D E FG H 1 4 H G F ED C B A 4 2 1 3 H A 4 H G F ED C B A 1 B C A 7 1 2 8 Conventional Midsection (CMS) Power Trim Page 6C-4 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Mechanical Power Trim Wiring Diagram a - PCM connector A b - PCM connector B c - PCM connector C d - Power trim motor e - +12 volts power f - Down relay g - –12 volts ground h - Up relay i - Power trim harness connector j - Power trim harness connector—PCM side k - Trim position sensor connector l - Cowl tilt switch m - Clean power connector n - 14‑pin connector IMPORTANT: Numerical callouts shown in the circuit diagrams are test points. Refer to Troubleshooting the Down Circuit or Troubleshooting the Up Circuit. Conventional Midsection (CMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6C-5
DTS Power Trim Wiring Diagram 64671 A1 A3 H4 30 85 86 87 87a 30 85 86 87 87a C2E3C3E4 A1 H4 A1M4C2 C B A 30 85 86 87 86 30 87 85 87a 87 87a 86 85 30 RELAY KEY Relay Components as Viewed Separated Relay Connector K JHG F E D C B A K JHG F E D C B A 1 3 2 4 M A M L M L 1 4 A BC D E FG H 2 4 1 3 H A A BC D E FG H 1 4 H G F ED C B A 4 2 1 3 H A 4 H G F ED C B A 1 308786 85 308786 85 308786 85 A BC B C A B C A 1 2 3 4 1 2 3 4 1 2 3 1 2 1 3 3 LT BLU/WHT LT BLU/WHT GRN/WHT YEL PPL/BLK BLK/GRN PPL/BLK BLK/GRN LT BLU/WHT GRN/WHT GRN/WHT YEL RED RED RED RED S109B LT BLU/WHT GRN/WHT RED LT BLU/WHT GRN/WHT RED LT BLU/WHT BLU RED RED RED RED BLU GRN GRN/WHT GRN BLK RED RED BLK BLK BLK b a d e f g h i j l k m e 3 7 7 6 4 c 1 5 2 8 Conventional Midsection (CMS) Power Trim Page 6C-6 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
DTS Power Trim Wiring Diagram a - PCM connector A b - PCM connector B c - PCM connector C d - Power trim motor e - +12 volts power f - Down relay g - –12 volts ground h - Up relay i - Power trim harness connector j - Power trim harness connector—PCM side k - Trim position sensor connector l - Cowl tilt switch m - Main power relay IMPORTANT: Numerical callouts shown in the circuit diagrams are test points. Refer to Troubleshooting the Down Circuit or Troubleshooting the Up Circuit. Troubleshooting the Down Circuit IMPORTANT: Refer to the preceding wiring diagrams for connection points when troubleshooting the electrical systems. Connection points are specified by number. Refer to the correct diagram for your engine (mechanical or DTS). DMT 2004 Digital Multimeter 91‑892647A01 IMPORTANT: Perform the following tests with the engine off and the 14‑pin connector disconnected from the outboard. This will isolate the outboard from the boat. If the engine tilts when using the cowl trim switch, the problem is related to the trim switch at the helm. NOTE: To access test points 2 and 8, partially remove the relay from the connector just far enough to reach the electrical contacts with the voltmeter lead. Step Test Procedure Test Result Step 1: Check for battery voltage at Point 1 by back probing. 1. Connect the voltmeter black lead to ground and the red lead to Point 1. 2. Depress the down trim button. Battery voltage measured: • Go to Step 2. No battery voltage measured: • Go to Step 3. Step 2: Check for battery voltage at Point 2. 1. Connect the voltmeter black lead to ground and the red lead to Point 2. 2. Depress the down trim button. Battery voltage measured: • Go to Step 5. No battery voltage measured: • There is an open circuit between Point 2 and the PCM. • Check for loose or corroded connections. • Inspect the wiring harness for opens, shorts, or damage. Repair or replace the harness. Step 3: Check for continuity between Point 1 and Point 5. 1. Disconnect the 3‑pin connector. 2. Connect the voltmeter black lead to Point 1 and the red lead to Point 5. Continuity measured (resistance should be 5.6 kΩ ± 20%): • Harness and PCM are OK. • Go to Step 4. No continuity measured (resistance should be 5.6 kΩ ± 20%): • Inspect the wiring harness for opens, shorts, or damage. Repair or replace the harness. Step 4: Check for battery voltage at Point 6. 1. Connect the voltmeter red lead to Point 6 and black lead to ground. Battery voltage measured: • Trim switch is faulty. No battery voltage measured: • Check for loose or corroded wire at Point 6. • Open circuit in wire supplying current between Point 6 and Point 7. Step 5: Check for battery voltage at Point 3. 1. Connect the voltmeter red lead to Point 3 (female bullet connector) and black lead to ground. 2. Depress the down trim button. Battery voltage measured: • Go to Step 6. No battery voltage measured: • Relay is defective. Conventional Midsection (CMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6C-7
Step Test Procedure Test Result Step 6: Check the up relay. 1. Connect the voltmeter red lead to Point 4 (female bullet connector) and black lead to ground. 2. Depress the up trim button. Relay is good (battery voltage measured): • Pump motor wiring is defective. • Pump motor is defective. Relay is faulty (no battery voltage measured): • Replace relay. Troubleshooting the Up Circuit IMPORTANT: Refer to the preceding wiring diagrams for connection points when troubleshooting the electrical systems. Connection points are specified by number. Refer to the correct diagram for your engine (mechanical or DTS). DMT 2004 Digital Multimeter 91‑892647A01 IMPORTANT: Perform the following tests with the engine off and the 14‑pin connector disconnected from the outboard. This will isolate the outboard from the boat. If the engine tilts when using the cowl trim switch, the problem is related to the trim switch at the helm. NOTE: To access test points 2 and 8, partially remove the relay from the connector just far enough to reach the electrical contacts with the voltmeter lead. Step Test Procedure Test Result Step 1: Check for battery voltage at Point 5 by back probing. 1. Connect the voltmeter black lead to ground and the red lead to Point 5. 2. Depress the up trim button. Battery voltage measured: • Go to Step 2. No battery voltage measured: • Go to Step 3. Step 2: Check for battery voltage at Point 8. 1. Connect the voltmeter black lead to ground and the red lead to Point 8. 2. Depress the up trim button. Battery voltage measured: • Go to Step 5. No battery voltage measured: • There is an open circuit between Point 8 and the PCM. • Check for loose or corroded connections. • Inspect the wiring harness for opens, shorts, or damage. Repair or replace the harness. Step 3: Check for continuity between Point 1 and Point 5. 1. Disconnect the 3‑pin connector. 2. Connect the voltmeter black lead to Point 1 and the red lead to Point 5. Continuity measured (resistance should be 5.6 kΩ ± 20%): • Harness and PCM are OK. • Go to Step 4. No continuity measured (resistance should be 5.6 kΩ ± 20%): • Inspect the wiring harness for opens, shorts, or damage. Repair or replace the harness. Step 4: Check for battery voltage at Point 6. 1. Connect the voltmeter red lead to Point 6 and black lead to ground. Battery voltage measured: • Trim switch is faulty. No battery voltage measured: • Check for loose or corroded wire at Point 6. • Open circuit in wire supplying current between Point 6 and Point 7. Step 5: Check for battery voltage at Point 4. 1. Connect the voltmeter red lead to Point 4 (female bullet connector) and black lead to ground. 2. Depress the up trim button. Battery voltage measured: • Go to Step 6. No battery voltage measured: • Relay is defective. Step 6: Check the down relay. 1. Connect the voltmeter red lead to Point 3 (female bullet connector) and black lead to ground. 2. Depress the down trim button. Relay is good (battery voltage measured): • Pump motor wiring is defective. • Pump motor is defective. Relay is faulty (no battery voltage measured): • Replace relay. Conventional Midsection (CMS) Power Trim Page 6C-8 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Troubleshooting the Down and Up Circuits (All Circuits Inoperative) IMPORTANT: Refer to the preceding wiring diagrams for connection points when troubleshooting the electrical systems. Connection points are specified by number. Refer to the correct diagram for your engine (mechanical or DTS). DMT 2004 Digital Multimeter 91‑892647A01 Problem Possible Cause Remedy The up and down trim switches are both inoperative, but the cowl switch does operate. 1. Faulty trim switch. 2. A wire is open between the trim pump motor and the trim switch. 1. Replace the trim switch. 2. Check for a loose or corroded connection. Trim switch and cowl switch are both inoperative. 1. One of the trim pump motor wires is open between the motor and the relays. 2. A wire is open between the trim pump motor and the trim switch. 3. Faulty trim relay. 4. Faulty trim pump motor. 1. Check the wire connections at point 2 or 8 for loose or corroded condition. 2. If voltage is present at the connections at point 2 or 8 when the appropriate trim button is pressed, the relays are okay. 3. Check if voltage is present at point 3 or 4 when the appropriate trim button is pressed. If voltage is not present, check for an open connection or a cut wire. 4. If voltage is present at point 3 or 4 when the appropriate trim button is pressed, replace the trim pump motor. Trim system operates (trim motor runs) without pressing the trim switch at the helm or the cowl trim switch. The trim switch at the helm or the cowl trim switch is shorted. Disconnect each trim switch. If the trim motor stops running when either trim switch is disconnected, replace the trim switch. Trim Circuit When the trim relays are de‑energized, contacts 30 and 87a of both relays complete the circuit to the trim motor leads. Both trim motor leads are to ground. Conventional Midsection (CMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6C-9
Trim Up Circuit When contact 86 of the trim up relay is energized from the trim switch, the trim up relay is energized. Contacts 30 and 87 of the trim up relay close, completing the circuit to 12 volts (+) to the blue trim motor lead. The trim down relay remains de‑energized. The trim motor tilts the engine up. Trim up circuit a - Trim relay contacts b - Trim up relay c - 12 volts (+) d - To trim motor (+) e - Trim down relay f - To trim motor (–) g - From PCM 85 86 30 87a 87 85 86 30 87a 87GRN RED BLK (+) (+) (+) 67464 a g c d f b e GRN/WHT (–) LT BLU/WHT (+) (+) RED 86 30 87 85 87a 87 87a 86 85 30 RELAY KEY Relay Components as Viewed Separated Relay Connector (–) (–) RED RED BLU Conventional Midsection (CMS) Power Trim Page 6C-10 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Trim Down Circuit When contact 86 of the trim down relay is energized from the trim switch, the trim down relay is energized. Contacts 30 and 87 of the trim down relay close, completing the circuit to 12 volts (+) to the green trim motor lead. The trim up relay remains de‑energized. The trim motor tilts the engine down. Trim down circuit a - Trim relay contacts b - Trim up relay c - To trim motor (–) d - 12 volts (+) e - Trim down relay f - To trim motor (+) g - From PCM Power Trim Relay Test IMPORTANT: The starboard intake plenum must be removed to access the power trim relays. Refer to the appropriate service manual for instructions. IMPORTANT: To remove the power trim relays, press the relay lock tab with your finger and pull the relay out of the bracket. Do not pull with the wires. a - Trim relay ground wire screw b - Trim up relay c - Trim down relay d - Main power relay e - Relay bracket screws The trim motor relay system, used on permanent magnet trim systems, connects each of the two wires from the trim motor to either ground or positive to allow the motor to run in both directions. 85 86 30 87a 87 85 86 30 87a 87GRN BLU RED RED BLK (+) (+) (+) 67466 a g d c f b e (–) GRN/WHT LT BLU/WHT (+) RED (+) RED 86 30 87 85 87a 87 87a 86 85 30 RELAY KEY Relay Components as Viewed Separated Relay Connector (–) (–) 63521 a be b c d Conventional Midsection (CMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6C-11
If the motor will not run in the up direction, it may be either the up relay is not making contact to 12 volts or the down relay is not making contact to ground. The opposite is true if the system will not run down. When the system is not energized, both relays should connect the heavy trim motor leads to ground. To test which relay is faulty if the trim system does not operate in one direction: 1. Remove the starboard intake plenum. Refer to the appropriate service manual for instructions. 2. Remove the relay from the bracket. 3. Partially remove the relay from the connector just far enough to reach the electrical contacts with the voltmeter lead. 4. Check for continuity between the heavy leads from the trim relays to ground. DMT 2004 Digital Multimeter 91‑892647A01 Meter Test Leads Meter Scale Reading (Ω) Red Black Green Ground Full continuity (R x 1) or Auto < 0.5 Ω Blue Ground Full continuity (R x 1) or Auto < 0.5 Ω 5. Replace the relay that does not have continuity. 6. Connect a voltmeter to the heavy blue lead and to ground. There should be 12 volts on the blue lead when the up switch is pushed and 12 volts on the green lead when the down switch is pushed. Replace the relay that does not switch the lead to positive. 7. Install the starboard intake plenum. Refer to the appropriate service manual for instructions. Trim Position Sensor Troubleshooting Trim Position Sensor The trim position sensor (TPS) is located on the port side of the outboard. It supplies the propulsion control module (PCM) with trim position information. The PCM will generate and store a failure code when the TPS fails, and the alarm horn will sound. The trim position sensor affects trim functions controlled by the helm trim switch and the cowl tilt switch. With the engine running below 2000 RPM, the outboard can be tilted to any position in the trim range or the trailer range. If above 2000 RPM, the trim range will be limited to prevent the outboard from reaching the trailer range. However, if you are loading the boat onto the trailer for example, and tilt the outboard up into the trailer range while below 2000 RPM, the throttle can be advanced to a maximum of 4400 RPM. The following are some of the problems encountered with a faulty trim position sensor: • Engine will trim higher than the set trim limit at speeds above 2000 RPM • Engine trims past the maximum trailer limits • Engine trims normally, but there are no trailer limits Troubleshooting the Trim Position Circuit Monitor the trim position sensor analog‑to‑digital counts (ADC) with CDS G3. Verify wiring harness integrity with a DMT 2004 digital multimeter or equivalent. DMT 2004 Digital Multimeter 91‑892647A01 Conventional Midsection (CMS) Power Trim Page 6C-12 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Step Test Procedure Test Result Step 1: Check trim position sensor using the trim gauge. 1. Turn key to the ON position. 2. Trim the engine up and down. 3. Observe the trim position gauge on the instrument panel. Trim position gauge varies with engine trim position: • Trim position sensor is good. • Go to Step 2. Trim position gauge does not vary with engine trim position: • Go to Step 2. Step 2: Check trim position sensor using CDS G3. 1. Turn key to the OFF position. 2. Connect the CDS G3 to the engine. 3. Turn key to the ON position. 4. Observe the trim position sensor counts on the CDS G3. 5. Trim the engine up and down. Count increases as engine trims up and decreases as engine trims down: • Trim position sensor is good. Count does not vary with engine trim position: • Go to Step 3. Step 3: Check sensor voltage. 1. Turn key to the OFF position. 2. Connect the trim position sensor connector. 3. Turn key to the ON position. 4. Check the sensor power between purple/ black and black/green wires. Voltage measured is 4.0–5.0 VDC: • Go to Step 4. Voltage measured is out of specified range: • Monitor the 5 V reference at the PCM with CDS G3. If reference voltage is OK, inspect the PCM harness for opens or shorts. Repair or replace as necessary. • If the 5 V reference at the PCM is not present or is out of range, PCM replacement may be necessary. Step 4: Inspect the magnet in the trim rod eye pin. 1. Remove the trim position sensor. 2. Inspect the magnet in the trim rod eye pin. If the magnet is corroded, damaged, or missing, there will not be a normal trim signal. Magnet is present and not damaged or corroded: • Go to Step 5. Magnet is missing, damaged, or corroded: 1. Replace the trim rod eye pin and magnet and install the trim position sensor. 2. Tilt the engine and monitor the trim position. If the trim position indicated does not change while tilting the engine, go to Step 5. Step 5: Check PCM harness for open or short circuit. 1. Turn key to the OFF position. 2. Disconnect the CDS G3 from the engine. 3. Disconnect the trim position sensor connector. Refer to Trim Position Sensor Location, following. 4. Check the resistance from the TPS connector to the PCM harness connector pins (PCM harness side): a. PCM C, pin E3 to black/green wire. b. PCM B, pin C2 to yellow wire. c. PCM C, pin E4 to purple/black wire. Resistance measured is less than 0.8 ohms: • Replace trim position sensor. Resistance measured is greater than 0.8 ohms: • PCM harness may be faulty. Conventional Midsection (CMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6C-13
Trim Position Sensor Location Conventional Midsection (CMS) a - Screw b - Screws (2) c - Trim position sensor d - Tilt lock lever Trim position sensor connector a - Port lower cowl b - Trim position sensor connector Testing the Trim Position Sensor Circuit with DMT 2004A The trim position sensor requires a 5‑volt reference signal from the PCM. Check for reference signal voltage with the ignition switch in the RUN position and using an appropriate probe (paper clip, etc.) inserted at the trim position sensor harness connector. DMT 2004 Digital Multimeter 91‑892647A01 Meter Test Leads Meter Scale Reading Red Black Purple/black Black/green VDC 5.0 ± 0.1 V If voltage is not as indicated or voltage is erratic, inspect the sensor wiring and connections. IMPORTANT: The 5‑volt reference at the PCM can be monitored by the CDS G3. Voltage should be 5.0 VDC ± 0.1 VDC. Any other voltage indicates a defective PCM. If the PCM reference voltage is correct, but voltage at the trim sensor is low or nonexistent, inspect the sensor wiring and connections. Check the resistance of the trim position sensor circuit harness and PCM. DMT 2004 Digital Multimeter 91‑892647A01 Meter Test Leads Meter Scale Reading Red Black Yellow Black/green Ohms 210 kΩ ± 20% If the resistance is not as indicated, inspect the sensor wiring and connections. 63439 a b c d a b 65861 Conventional Midsection (CMS) Power Trim Page 6C-14 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Trim Switches and Sensor ‑ DTS a - PCM connector A b - PCM connector B c - PCM connector C d - Trim harness connector e - Trim position sensor connector f - Cowl tilt switch connector g - Hot stud (battery +) Connector Pin Wire Color Function PCM 65763 C B A A Red 12 V battery power (+) – B Green/white Trim down relay control BM4 C Light blue/white Trim up relay control AA3 65697 4 3 1 2 1 N/A Not used – 2 Black/green Sensor ground C (–) CE3 3 Yellow Trim position sensor signal BC2 4 Purple/black Sensor power C (+) CE4 65695 1 2 3 1 Red 12 V battery power (+) – 2 Green/white Trim down (from switch) CC3 3 Light blue/white Trim up (from switch) CC2 S109B GRN/WHT YEL PPL/BLK BLK/GRN LT BLU/WHT GRN/WHT RED LT BLU/WHT LT BLU/WHT GRN/WHT GRN/WHT RED RED YEL PPL/BLK BLK/GRN LT BLU/WHT 3 2 1 H4 C2 C3 E3E4 A1 C2 M4 A1 A1 A3 H4 2 3 4 1 A BC A B C D E F G H 1 2 3 4 A B C D E F G H A B C D E F G H J K A B C D E F G H J K 3 1 4 2 L M L M A B C D E F G H 1 2 3 4 A B C D E F G H M A 4 1 A H 1 4 H A 4 1 1 2 3 65916 a b c d e f g Conventional Midsection (CMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6C-15
Trim Switches and Sensor ‑ Mechanical a - PCM connector A b - PCM connector B c - PCM connector C d - Trim harness connector e - Trim position sensor connector f - Cowl tilt switch connector g - Clean power harness connector h - 14‑pin data harness connector Connector Pin Wire Color Function PCM 65763 C B A A Red/black 12 V clean power (+) * B Green/white Trim down relay control BM4 C Light blue/white Trim up relay control AA3 65697 4 3 1 2 1 N/A Not used – 2 Black/green Sensor ground C (–) CE3 3 Yellow Trim position sensor signal BC2 4 Purple/black Sensor power C (+) CE4 65695 1 2 3 1 Red/black 12 V clean power (+) * 2 Green/white Trim down (from switch) CC3 3 Light blue/white Trim up (from switch) CC2 Clean power harness B Black Clean power ground (–) – *Clean power is in input to the PCM at pin CA4, not shown. S115 S114A S107 S112 S114B GRN/WHT YEL BLK RED/BLK LT BLU/WHT GRN/WHT PPL/BLK BLK/GRN LT BLU/WHT GRN/WHT BLK RED/BLK LT BLU/WHT LT BLU/WHT GRN/WHT GRN/WHT RED/BLK RED/BLK YEL PPL/BLK BLK/GRN LT BLU/WHT B A 1 2 3 2 3 4 1 A BC H4 C2 C3 E3E4 A1 C2 M4 A1 A1 A3 H4 A BC D E FG H JK LM N P A B 1 2 3 N K J HG F E C B A M D L P A B C D E F G H 1 2 3 4 A B C D E F G H A B C D E F G H J K A B C D E F G H J K 3 1 4 2 L M L M A B C D E F G H 1 2 3 4 A B C D E F G H M A 4 1 A H 1 4 H A 4 1 1 2 3 A B A B 1 2 3 H J K M C F P 65915 a b c d e f g h Conventional Midsection (CMS) Power Trim Page 6C-16 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Electrical Systems Section 6D - Advanced Midsection (AMS) Power Trim Table of Contents Electrical System Troubleshooting.................................... 6D-2 General Checks..........................................................6D-2 Condition/Problem...................................................... 6D-2 Problem/Solution........................................................ 6D-2 Power Trim Electrical Circuit...................................... 6D-2 Troubleshooting the Down Circuit.............................. 6D-5 Troubleshooting the Up Circuit................................... 6D-6 Troubleshooting the Down and Up Circuits (All Circuits Inoperative)................................................ 6D-7 Trim Circuit........................................................................ 6D-7 Trim Up Circuit............................................................6D-8 Trim Down Circuit....................................................... 6D-9 Power Trim Relay Test...................................................... 6D-9 Trim Position Sensor Troubleshooting.............................6D-10 Trim Position Sensor................................................ 6D-10 Troubleshooting the Trim Position Circuit.................6D-10 Trim Position Sensor Location..................................6D-12 Testing the Trim Position Sensor with DMT 2004A..6D-12 Trim Switches and Sensor ‑ DTS.................................... 6D-13 Advanced Midsection (AMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6D-1 6 D
Special Tools DMT 2004 Digital Multimeter 91‑892647A01 A m A C O M V H z mV V H z TEMP m A A IG OFF IP H z TEMP 4516 Measures RPM on spark ignition (SI) engines, ohms, amperes, AC and DC voltages; records maximums and minimums simultaneously, and accurately reads in high RFI environments. Electrical System Troubleshooting General Checks Before troubleshooting the power trim electrical system, check for the following: • Disconnected wires • Battery is fully charged • Battery cable connections are tight and corrosion‑free • Battery cables are secured with hex nuts, not wing nuts • Connections are tight and corrosion‑free • Plug‑in connections are fully engaged • Clean power is connected Condition/Problem Condition of Trim System Problem No. Trim motor does not run when trim button is depressed 1, 2, 4, 5, 6, 7 Trim system trims opposite of buttons 3 Cowl‑mounted trim buttons do not activate trim system 2, 4, 5, 6 Problem/Solution No. Problem Solution 1. Battery low or discharged Check the battery. 2. Open circuit in trim wiring Check for an open connection. 3. Wiring reversed in remote control, cowl switch, or trim leads Verify connections. 4. Wire harness corroded through Replace wire harness. 5. Internal motor problem (brushes, shorted armature) Check for an open connection. Test and replace the power trim motor if necessary. 6. Trim switch failure Replace the switch. 7. Relay not operating Verify relays are functioning correctly. Check voltage at the power trim bullet connectors. Power Trim Electrical Circuit IMPORTANT: Numerical callouts shown in the circuit diagrams are test points. Refer to Troubleshooting the Down Circuit or Troubleshooting the Up Circuit. Advanced Midsection (AMS) Power Trim Page 6D-2 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Advanced Midsection (AMS) Power Trim Notes: 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6D-3
DTS Power Trim Wiring Diagram 64671 A1 A3 H4 30 85 86 87 87a 30 85 86 87 87a C2E3C3E4 A1 H4 A1M4C2 C B A 30 85 86 87 86 30 87 85 87a 87 87a 86 85 30 RELAY KEY Relay Components as Viewed Separated Relay Connector K JHG F E D C B A K JHG F E D C B A 1 3 2 4 M A M L M L 1 4 A BC D E FG H 2 4 1 3 H A A BC D E FG H 1 4 H G F ED C B A 4 2 1 3 H A 4 H G F ED C B A 1 308786 85 308786 85 308786 85 A BC B C A B C A 1 2 3 4 1 2 3 4 1 2 3 1 2 1 3 3 LT BLU/WHT LT BLU/WHT GRN/WHT YEL PPL/BLK BLK/GRN PPL/BLK BLK/GRN LT BLU/WHT GRN/WHT GRN/WHT YEL RED RED RED RED S109B LT BLU/WHT GRN/WHT RED LT BLU/WHT GRN/WHT RED LT BLU/WHT BLU RED RED RED RED BLU GRN GRN/WHT GRN BLK RED RED BLK BLK BLK b a d e f g h i j l k m e 3 7 7 6 4 c 1 5 2 8 Advanced Midsection (AMS) Power Trim Page 6D-4 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
DTS Power Trim Wiring Diagram a - PCM connector A b - PCM connector B c - PCM connector C d - Power trim motor e - +12 volts power f - Down relay g - –12 volts ground h - Up relay i - Power trim harness connector j - Power trim harness connector—PCM side k - Trim position sensor connector l - Cowl tilt switch m - Main power relay IMPORTANT: Numerical callouts shown in the circuit diagrams are test points. Refer to Troubleshooting the Down Circuit or Troubleshooting the Up Circuit. Troubleshooting the Down Circuit IMPORTANT: Refer to the preceding wiring diagram for connection points when troubleshooting the electrical systems. Connection points are specified by number. DMT 2004 Digital Multimeter 91‑892647A01 IMPORTANT: Perform the following tests with the engine off and the 14‑pin connector disconnected from the outboard. This will isolate the outboard from the boat. If the engine tilts when using the cowl trim switch, the problem is related to the trim switch at the helm. NOTE: To access test points 2 and 8, partially remove the relay from the connector just far enough to reach the electrical contacts with the voltmeter lead. Step Test Procedure Test Result Step 1: Check for battery voltage at Point 1 by back probing. 1. Connect the voltmeter black lead to ground and the red lead to Point 1. 2. Depress the down trim button. Battery voltage measured: • Go to Step 2. No battery voltage measured: • Go to Step 3. Step 2: Check for battery voltage at Point 2. 1. Connect the voltmeter black lead to ground and the red lead to Point 2. 2. Depress the down trim button. Battery voltage measured: • Go to Step 5. No battery voltage measured: • There is an open circuit between Point 2 and the PCM. • Check for loose or corroded connections. • Inspect the wiring harness for opens, shorts, or damage. Repair or replace the harness. Step 3: Check for continuity between Point 1 and Point 5. 1. Disconnect the 3‑pin connector. 2. Connect the voltmeter black lead to Point 1 and the red lead to Point 5. Continuity measured (resistance should be 5.6 kΩ ± 20%): • Harness and PCM are OK. • Go to Step 4. No continuity measured (resistance should be 5.6 kΩ ± 20%): • Inspect the wiring harness for opens, shorts, or damage. Repair or replace the harness. Step 4: Check for battery voltage at Point 6. 1. Connect the voltmeter red lead to Point 6 and black lead to ground. Battery voltage measured: • Trim switch is faulty. No battery voltage measured: • Check for loose or corroded wire at Point 6. • Open circuit in wire supplying current between Point 6 and Point 7. Step 5: Check for battery voltage at Point 3. 1. Connect the voltmeter red lead to Point 3 (female bullet connector) and black lead to ground. 2. Depress the down trim button. Battery voltage measured: • Go to Step 6. No battery voltage measured: • Relay is defective. Advanced Midsection (AMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6D-5
Step Test Procedure Test Result Step 6: Check the up relay. 1. Connect the voltmeter red lead to Point 4 (female bullet connector) and black lead to ground. 2. Depress the up trim button. Relay is good (battery voltage measured): • Pump motor wiring is defective. • Pump motor is defective. Relay is faulty (no battery voltage measured): • Replace relay. Troubleshooting the Up Circuit IMPORTANT: Refer to the preceding wiring diagram for connection points when troubleshooting the electrical systems. Connection points are specified by number. DMT 2004 Digital Multimeter 91‑892647A01 IMPORTANT: Perform the following tests with the engine off and the 14‑pin connector disconnected from the outboard. This will isolate the outboard from the boat. If the engine tilts when using the cowl trim switch, the problem is related to the trim switch at the helm. NOTE: To access test points 2 and 8, partially remove the relay from the connector just far enough to reach the electrical contacts with the voltmeter lead. Step Test Procedure Test Result Step 1: Check for battery voltage at Point 5 by back probing. 1. Connect the voltmeter black lead to ground and the red lead to Point 5. 2. Depress the up trim button. Battery voltage measured: • Go to Step 2. No battery voltage measured: • Go to Step 3. Step 2: Check for battery voltage at Point 8. 1. Connect the voltmeter black lead to ground and the red lead to Point 8. 2. Depress the up trim button. Battery voltage measured: • Go to Step 5. No battery voltage measured: • There is an open circuit between Point 8 and the PCM. • Check for loose or corroded connections. • Inspect the wiring harness for opens, shorts, or damage. Repair or replace the harness. Step 3: Check for continuity between Point 1 and Point 5. 1. Disconnect the 3‑pin connector. 2. Connect the voltmeter black lead to Point 1 and the red lead to Point 5. Continuity measured (resistance should be 5.6 kΩ ± 20%): • Harness and PCM are OK. • Go to Step 4. No continuity measured (resistance should be 5.6 kΩ ± 20%): • Inspect the wiring harness for opens, shorts, or damage. Repair or replace the harness. Step 4: Check for battery voltage at Point 6. 1. Connect the voltmeter red lead to Point 6 and black lead to ground. Battery voltage measured: • Trim switch is faulty. No battery voltage measured: • Check for loose or corroded wire at Point 6. • Open circuit in wire supplying current between Point 6 and Point 7. Step 5: Check for battery voltage at Point 4. 1. Connect the voltmeter red lead to Point 4 (female bullet connector) and black lead to ground. 2. Depress the up trim button. Battery voltage measured: • Go to Step 6. No battery voltage measured: • Relay is defective. Step 6: Check the down relay. 1. Connect the voltmeter red lead to Point 3 (female bullet connector) and black lead to ground. 2. Depress the down trim button. Relay is good (battery voltage measured): • Pump motor wiring is defective. • Pump motor is defective. Relay is faulty (no battery voltage measured): • Replace relay. Advanced Midsection (AMS) Power Trim Page 6D-6 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Troubleshooting the Down and Up Circuits (All Circuits Inoperative) IMPORTANT: Numerical callouts shown in the circuit diagrams are test points. Refer to Troubleshooting the Down Circuit or Troubleshooting the Up Circuit. DMT 2004 Digital Multimeter 91‑892647A01 Problem Possible Cause Remedy The up and down trim switches are both inoperative, but the cowl switch does operate. 1. Faulty trim switch. 2. A wire is open between the trim pump motor and the trim switch. 1. Replace the trim switch. 2. Check for a loose or corroded connection. Trim switch and cowl switch are both inoperative. 1. One of the trim pump motor wires is open between the motor and the relays. 2. A wire is open between the trim pump motor and the trim switch. 3. Faulty trim relay. 4. Faulty trim pump motor. 1. Check the wire connections at point 2 or 8 for loose or corroded condition. 2. If voltage is present at the connections at point 2 or 8 when the appropriate trim button is pressed, the relays are okay. 3. Check if voltage is present at point 3 or 4 when the appropriate trim button is pressed. If voltage is not present, check for an open connection or a cut wire. 4. If voltage is present at point 3 or 4 when the appropriate trim button is pressed, replace the trim pump motor. Trim system operates (trim motor runs) without pressing the trim switch at the helm or the cowl trim switch. The trim switch at the helm or the cowl trim switch is shorted. Disconnect each trim switch. If the trim motor stops running when either trim switch is disconnected, replace the trim switch. Trim Circuit When the trim relays are de‑energized, contacts 30 and 87a of both relays complete the circuit to the trim motor leads. Both trim motor leads are to ground. Advanced Midsection (AMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6D-7
Trim Up Circuit When contact 86 of the trim up relay is energized from the trim switch, the trim up relay is energized. Contacts 30 and 87 of the trim up relay close, completing the circuit to 12 volts (+) to the blue trim motor lead. The trim down relay remains de‑energized. The trim motor tilts the engine up. Trim up circuit a - Trim relay contacts b - Trim up relay c - 12 volts (+) d - To trim motor (+) e - Trim down relay f - To trim motor (–) g - From PCM 85 86 30 87a 87 85 86 30 87a 87GRN RED BLK (+) (+) (+) 67464 a g c d f b e GRN/WHT (–) LT BLU/WHT (+) (+) RED 86 30 87 85 87a 87 87a 86 85 30 RELAY KEY Relay Components as Viewed Separated Relay Connector (–) (–) RED RED BLU Advanced Midsection (AMS) Power Trim Page 6D-8 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Trim Down Circuit When contact 86 of the trim down relay is energized from the trim switch, the trim down relay is energized. Contacts 30 and 87 of the trim down relay close, completing the circuit to 12 volts (+) to the green trim motor lead. The trim up relay remains de‑energized. The trim motor tilts the engine down. Trim down circuit a - Trim relay contacts b - Trim up relay c - To trim motor (–) d - 12 volts (+) e - Trim down relay f - To trim motor (+) g - From PCM Power Trim Relay Test IMPORTANT: The starboard intake plenum must be removed to access the power trim relays. Refer to the appropriate service manual for instructions. IMPORTANT: To remove the power trim relays, press the relay lock tab with your finger and pull the relay out of the bracket. Do not pull with the wires. a - Trim relay ground wire screw b - Trim up relay c - Trim down relay d - Main power relay e - Relay bracket screws The trim motor relay system, used on permanent magnet trim systems, connects each of the two wires from the trim motor to either ground or positive to allow the motor to run in both directions. 85 86 30 87a 87 85 86 30 87a 87GRN BLU RED RED BLK (+) (+) (+) 67466 a g d c f b e (–) GRN/WHT LT BLU/WHT (+) RED (+) RED 86 30 87 85 87a 87 87a 86 85 30 RELAY KEY Relay Components as Viewed Separated Relay Connector (–) (–) 63521 a be b c d Advanced Midsection (AMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6D-9
If the motor will not run in the up direction, it may be either the up relay is not making contact to 12 volts or the down relay is not making contact to ground. The opposite is true if the system will not run down. When the system is not energized, both relays should connect the heavy trim motor leads to ground. To test which relay is faulty if the trim system does not operate in one direction: 1. Remove the starboard intake plenum. Refer to the appropriate service manual for instructions. 2. Remove the relay from the bracket. 3. Partially remove the relay from the connector just far enough to reach the electrical contacts with the voltmeter lead. 4. Check for continuity between the heavy leads from the trim relays to ground. DMT 2004 Digital Multimeter 91‑892647A01 Meter Test Leads Meter Scale Reading (Ω) Red Black Green Ground Full continuity (R x 1) or Auto < 0.5 Ω Blue Ground Full continuity (R x 1) or Auto < 0.5 Ω 5. Replace the relay that does not have continuity. 6. Connect a voltmeter to the heavy blue lead and to ground. There should be 12 volts on the blue lead when the up switch is pushed and 12 volts on the green lead when the down switch is pushed. Replace the relay that does not switch the lead to positive. 7. Install the starboard intake plenum. Refer to the appropriate service manual for instructions. Trim Position Sensor Troubleshooting Trim Position Sensor The trim position sensor (TPS) is located on the bottom of the mount cradle. It supplies the propulsion control module (PCM) with trim position information. The PCM will generate and store a failure code when the TPS fails, and the alarm horn will sound. The trim position sensor affects trim functions controlled by the helm trim switch and the cowl tilt switch. With the engine running below 2000 RPM, the outboard can be tilted to any position in the trim range or the trailer range. If above 2000 RPM, the trim range will be limited to prevent the outboard from reaching the trailer range. However, if you are loading the boat onto the trailer for example, and tilt the outboard up into the trailer range while below 2000 RPM, the throttle can be advanced to a maximum of 4400 RPM. The following are some of the problems encountered with a faulty trim position sensor: • Engine will trim higher than the set trim limit at speeds above 2000 RPM • Engine trims past the maximum trailer limits • Engine trims normally, but there are no trailer limits Troubleshooting the Trim Position Circuit Monitor the trim position sensor analog‑to‑digital counts (ADC) with the CDS G3. Verify wiring harness integrity with a DMT 2004 digital multimeter or equivalent. DMT 2004 Digital Multimeter 91‑892647A01 Advanced Midsection (AMS) Power Trim Page 6D-10 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Step Test Procedure Test Result Step 1: Check trim position sensor using the trim gauge. 1. Turn key to the ON position. 2. Trim the engine up and down. 3. Observe the trim position gauge on the instrument panel. Trim position gauge varies with engine trim position: • Trim position sensor is good. • Go to Step 2. Trim position gauge does not vary with engine trim position: • Go to Step 2. Step 2: Check trim position sensor using CDS G3. 1. Turn key to the OFF position. 2. Connect the CDS G3 to the engine. 3. Turn key to the ON position. 4. Observe the trim position sensor counts on the CDS G3. 5. Trim the engine up and down. Count increases as engine trims up and decreases as engine trims down: • Trim position sensor is good. Count does not vary with engine trim position: • Go to Step 3. Step 3: Check sensor voltage. 1. Turn key to the OFF position. 2. Connect the trim position sensor connector. 3. Turn key to the ON position. 4. Check the sensor power between purple/black and black/green wires. Voltage measured is 4.0–5.0 VDC: • Go to Step 4. Voltage measured is out of specified range: • Monitor the 5‑volt reference at the PCM with CDS G3. If reference voltage is OK, inspect the PCM harness for opens or shorts. Repair or replace as necessary. • If the 5‑volt reference at the PCM is not present or is out of range, PCM replacement may be necessary. Step 4: Inspect the magnet in the trim rod eye pin. 1. Remove the trim position sensor. 2. Inspect the magnet in the trim rod eye pin. If the magnet is corroded, damaged, or missing, there will not be a normal trim signal. Magnet is present and not damaged or corroded: • Go to Step 5. Magnet is missing, damaged, or corroded: 1. Replace the trim rod eye pin and magnet and install the trim position sensor. 2. Tilt the engine and monitor the trim position. If the trim position indicated does not change while tilting the engine, go to Step 5. Step 5: Check PCM harness for open or short circuit. 1. Turn key to the OFF position. 2. Disconnect the CDS G3 from the engine. 3. Disconnect the trim position sensor connector. Refer to Trim Position Sensor Location, following. 4. Check the resistance from the TPS connector to the PCM harness connector pins (PCM harness side): a. PCM C, pin E3 to black/green wire. b. PCM B, pin C2 to yellow wire. c. PCM C, pin E4 to purple/black wire. Resistance measured is less than 0.8 ohms: • Replace trim position sensor. Resistance measured is greater than 0.8 ohms: • PCM harness may be faulty. Advanced Midsection (AMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6D-11
Trim Position Sensor Location a - Trim position sensor magnet b - Screws (2) c - Trim position sensor d - Tilt lock bracket Port side of outboard a - Port lower cowl b - Trim position sensor connector Testing the Trim Position Sensor with DMT 2004A The trim sensor requires a 5‑volt reference signal from the PCM. Check for reference signal voltage with the ignition switch in the RUN position and using an appropriate probe (paper clip, etc.) inserted in parallel at the trim sensor connector. DMT 2004 Digital Multimeter 91‑892647A01 Meter Test Leads Meter Scale Reading Red Black Purple/black Black/green VDC 5.0 ± 0.1 V IMPORTANT: The 5‑volt reference at the PCM can be monitored by the CDS G3. Voltage should be 5 VDC ± 0.1 VDC. Any other voltage indicates a defective PCM. If the PCM reference voltage is correct, but voltage at the trim sensor is low or nonexistent, inspect the sensor wiring and connections. Check the resistance of the trim position sensor circuit harness and PCM. DMT 2004 Digital Multimeter 91‑892647A01 Meter Test Leads Meter Scale Reading Red Black Yellow Black/green Ohms 210 kΩ ± 20% a b c d 67093 a b 65861 Advanced Midsection (AMS) Power Trim Page 6D-12 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Trim Switches and Sensor ‑ DTS a - PCM connector A b - PCM connector B c - PCM connector C d - Trim harness connector e - Trim position sensor connector f - Cowl tilt switch connector g - Hot stud (battery +) Connector Pin Wire Color Function PCM 65763 C B A A Red 12 V battery power (+) – B Green/white Trim down relay control BM4 C Light blue/white Trim up relay control AA3 65697 4 3 1 2 1 N/A Not used – 2 Black/green Sensor ground C (–) CE3 3 Yellow Trim position sensor signal BC2 4 Purple/black Sensor power C (+) CE4 65695 1 2 3 1 Red 12 V battery power (+) – 2 Green/white Trim down (from switch) CC3 3 Light blue/white Trim up (from switch) CC2 S109B GRN/WHT YEL PPL/BLK BLK/GRN LT BLU/WHT GRN/WHT RED LT BLU/WHT LT BLU/WHT GRN/WHT GRN/WHT RED RED YEL PPL/BLK BLK/GRN LT BLU/WHT 3 2 1 H4 C2 C3 E3E4 A1 C2 M4 A1 A1 A3 H4 2 3 4 1 A BC A B C D E F G H 1 2 3 4 A B C D E F G H A B C D E F G H J K A B C D E F G H J K 3 1 4 2 L M L M A B C D E F G H 1 2 3 4 A B C D E F G H M A 4 1 A H 1 4 H A 4 1 1 2 3 65916 a b c d e f g Advanced Midsection (AMS) Power Trim 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 6D-13
Advanced Midsection (AMS) Power Trim Notes: Page 6D-14 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Fuel System Section 7A - Fuel System Table of Contents Fuel System Specifications................................................7A-2 Fuel System Overview....................................................... 7A-2 Theory of Operation....................................................7A-2 Fuel System................................................................7A-2 Fuel Injector................................................................ 7A-2 In‑line Fuel Filter......................................................... 7A-3 V6 Fuel Flow Diagram................................................ 7A-4 V8 Fuel Flow Diagram................................................ 7A-6 Fuel Supply Module (FSM)................................................ 7A-7 Fuel Supply Module (FSM) Description...................... 7A-7 Fuel Pressure Regulator.............................................7A-8 Fuel Lift Pump.............................................................7A-8 High‑Pressure Fuel Pump.......................................... 7A-9 Fuel System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 7A-1 7 A
Fuel System Specifications Fuel System Specifications Recommended fuel octane rating 87 (R+M)/2, 91 RON Approximate fuel pressure at idle 290–340 kPa (42.1–43.9 psi) Approximate fuel pressure engine not running 340–370 kPa (49.3–53.7 psi) Fuel filtration Inlet filter, engine mounted 10 microns Inlet filter, remote boat mounted 10 microns High‑pressure, at fuel rail inlet 46 microns Fuel pump current draw 12 A ± 2 A (at 14.4 V) Maximum fuel system inlet vacuum 10.16 kPa (3.0 in. Hg), (1.47 psi) Fuel System Overview Theory of Operation The sequential multiport fuel injection system uses an electronic propulsion control module (PCM) and multiple input sensors to maintain optimum injector volume (pulse width) and injection timing control. Two fuel pumps are located inside a sealed, water‑cooled, fuel supply module (FSM). The FSM contains a fuel lift pump, a high‑pressure fuel pump, a fuel pressure regulator, and a fuel cooler. The FSM is mounted in front of the exhaust tube in the midsection of the engine. A reference hose on the intake manifold is connected to the fuel pressure regulator inside the FSM. Fuel is recirculated inside the FSM to regulate fuel rail pressure. The PCM uses data collected from the manifold absolute pressure (MAP) sensor to determine the ambient barometric (BARO) pressure and monitor pressure changes inside the plenum. An intake air temperature (IAT) sensor, located on the starboard intake runner, sends air temperature data to the PCM. Engine speed and valve position are monitored by a crankshaft position sensor (CPS) and a camshaft position sensor. An O2 sensor is mounted in the exhaust manifold to help monitor fuel delivery and maintain the ideal fuel‑to‑air ratio at the desired emissions target. Electronic throttle control (ETC) is modulated by the PCM. The PCM converts digital position signals from the ERC (DTS models) or throttle demand sensor (mechanical throttle and shift models) and positions the throttle plate accordingly. Two throttle position sensors (TPS) are used to ensure the accuracy of the throttle plate position. ETC also acts as an idle air control, increasing or decreasing the throttle plate opening as necessary to ensure optimum idle and performance characteristics. Fuel System ! WARNING Fuel is flammable and explosive. Ensure that the key switch is OFF and the lanyard is positioned so that the engine cannot start. Do not smoke or allow sources of spark or open flame in the area while servicing. Keep the work area well ventilated and avoid prolonged exposure to vapors. Always check for leaks before attempting to start the engine, and wipe up any spilled fuel immediately. IMPORTANT: Use an approved container to collect and store fuel. Wipe up spilled fuel immediately. Material used to contain spilled fuel must be disposed of in an approved receptacle. Before servicing any part of the fuel system: 1. Stop engine and disconnect the battery. 2. Perform fuel system service in a well‑ventilated area. 3. Inspect any completed service work for signs of fuel leakage. Fuel Injector The fuel injector is an electrically operated, spring‑loaded solenoid that delivers a metered amount of fuel into the intake manifold runner just ahead of the intake valves. The fuel injector is electrically charged when the key switch is set to the RUN position. The PCM completes the ground circuit of the injector, activating the injector's solenoid and allowing the flow of high‑pressure fuel into the combustion chamber. The PCM then opens the ground circuit, allowing the spring to close the injector and stop the fuel flow. There are two separate streams of fuel aimed at the intake valves, for better atomization of the fuel. The fuel injector is not serviceable. Fuel System Page 7A-2 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
The fuel injectors are not common to any other engine. Each fuel rail contains three fuel injectors on V6 models, or four fuel injectors on V8 models. a - Fuel rail b - Fuel injector In‑line Fuel Filter The in‑line fuel filter is located inside the inlet end of each fuel rail. This in‑line fuel filter consists of a one‑way, reusable filter element. In the event of fuel contamination, the filter element can be cleaned by backflushing the element with a locally available fuel system cleaner. Replacement is not required unless the in‑line fuel filter is damaged, punctured, or otherwise unsuitable for use. 55858 In-line fuel filter a b 66273 Fuel System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 7A-3
V6 Fuel Flow Diagram 15 16 17 18 19 20 21 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 66084 Fuel System Page 7A-4 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
1 - Port fuel rail 2 - Starboard rail and injectors 3 - Fuel inlet from vessel 4 - Starboard rail hose quick‑connect 5 - Filter to fuel supply module (FSM) hose 6 - FSM 7 - Manifold reference base hose 8 - FSM T‑fitting 9 - Manifold reference quick‑connect 10 - Port rail hose quick‑connect 11 - Port rail hose 12 - Water‑separating fuel filter 13 - Manifold reference 14 - Starboard rail hose 15 - High‑pressure to fuel rails 16 - Fuel pressure regulator 17 - Fuel cooler 18 - High‑pressure fuel pump 19 - Siphon tube 20 - Fuel cooler 21 - Fuel lift pump 22 - Recirculation check valve Fuel System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 7A-5
V8 Fuel Flow Diagram 15 16 17 18 19 20 21 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 66099 Fuel System Page 7A-6 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
1 - Port fuel rail 2 - Starboard rail and injectors 3 - Fuel inlet from vessel 4 - Starboard rail hose quick‑connect 5 - Filter to fuel supply module (FSM) hose 6 - FSM 7 - Manifold reference base hose 8 - FSM T‑fitting 9 - Manifold reference quick‑connect 10 - Port rail hose quick‑connect 11 - Port rail hose 12 - Water‑separating fuel filter 13 - Manifold reference 14 - Starboard rail hose 15 - High‑pressure to fuel rails 16 - Fuel pressure regulator 17 - Fuel cooler 18 - High‑pressure fuel pump 19 - Siphon tube 20 - Fuel cooler 21 - Fuel lift pump 22 - Recirculation check valve Fuel Supply Module (FSM) Fuel Supply Module (FSM) Description The FSM contains the fuel lift pump, high‑pressure fuel pump, fuel pressure regulator, and the fuel cooler. The filling of the FSM is provided by the positive displacement fuel lift pump. Modulation of the fuel lift pump is not required. The volume of entrained air in the FSM, high‑pressure fuel line, and fuel rail must be purged to allow the fuel to reach the top fuel injector on the fuel rail. When the FSM is properly purged, it is almost always completely filled. The fuel lift pump and the high‑pressure fuel pump are both powered by the same electrical circuit inside the FSM. Power from the fuel pump relay activates the fuel lift pump and the high‑pressure fuel pump. Fuel pressure is controlled by the fuel pressure regulator located inside the FSM. Cooling of the fuel occurs with a bi‑level heat transfer. Inside the FSM are four metal tubes: two that are large diameter and two that are smaller diameter. The smaller diameter tubes are inside the large diameter tubes. The large diameter metal tubes pass water that cools the reservoir fuel and the fuel that passes through the smaller diameter tubes from the high‑pressure pump and fuel pressure regulator. a - Fuel pressure regulator manifold reference port b - High‑pressure fuel out port c - Fuel cooler water out port to the water pump indicator d - Fuel lift pump (from vessel) e - Fuel cooler water in port from strainer f - Fuel cooler fuel tube c f a b c d e e c 47841 Fuel System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 7A-7
Fuel Pressure Regulator The fuel pressure regulator, located inside the fuel supply module, controls the amount of fuel pressure required for the engine to run efficiently. The fuel pressure regulator changes the pressurization of the fuel depending on the demands of the engine. Air pressure in the intake manifold changes to a higher or lower pressure during RPM changes. These manifold air pressure changes are linked to the fuel pressure regulator. The changes that take place at the fuel pressure regulator are managed by a hose that is connected to the intake manifold. The air pressure change that is positive or negative on the fuel pressure regulator diaphragm, increases or decreases the amount of fuel that is returned back into the FSM. The fuel pressure dumped by the fuel pressure regulator passes through a fuel cooler. Passing the excess fuel through the fuel cooler prevents the high‑pressure and low‑pressure fuel pumps from overheating. 47840 Fuel Lift Pump The fuel lift pump located inside the FSM pulls fuel from the fuel tank. The fuel lift pump is activated with 12 volts through the main power relay and the fuel pump control relay when there is no engine rotation, and the key is turned to the ON position for approximately three seconds. The propulsion control module (PCM) does not have the logic to detect the fuel lift pump operation. In the event of a fuel lift pump failure, no fault will be generated and the engine will not run. The fuel lift pump has fuel passing through it constantly when the FSM is full of fuel. A fuel recirculating check valve inside the FSM is conjoined with the fuel lift port passage. When fuel cannot be pulled into the FSM from the fuel tank (FSM is full), the check valve opens and allows the cooled fuel inside the FSM to pass through the fuel lift pump, preventing the pump from overheating. The FSM is a volume displacement module, which replaces the fuel inside the FSM automatically without the installation of a float switch or needle and seat. 47837 Fuel System Page 7A-8 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
High‑Pressure Fuel Pump When the ignition key is turned ON, the high‑pressure fuel pump is active for approximately three seconds. After the first three seconds, the high‑pressure fuel pump will not run until the PCM recognizes engine RPM. The PCM does not have the logic to detect the high‑pressure fuel pump operation. In the event of a high‑pressure fuel pump failure, no fault will be generated and the engine will not run. The high‑pressure fuel pump sends the fuel through a 20 micron fuel filter and into the bottom of the fuel rail. There is an internal overpressure relief of 689.5 kPa (100 psi) for the high‑pressure pump. The fuel rail pressure is controlled by a fuel pressure regulator. The fuel pressure dumped by the fuel pressure regulator passes through a fuel cooler. Passing the excessive fuel through the fuel cooler prevents the high‑pressure fuel pump from overheating. 47839 Fuel System 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 7A-9
Fuel System Notes: Page 7A-10 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021
Fuel System Section 7B - Troubleshooting and Diagnostics Table of Contents Fuel Component Troubleshooting and Diagnostics........... 7B-2 Anti‑siphon Valves...................................................... 7B-2 Fuel Supply Module (FSM)......................................... 7B-2 Fuel Lift Pump.............................................................7B-2 High‑Pressure Fuel Pump.......................................... 7B-3 Fuel Pressure Calculations, Engine Running............. 7B-4 Fuel Injector Resistance Test..................................... 7B-4 Wire Color Code Abbreviations.................................. 7B-4 Fuel Injector Circuits................................................... 7B-6 Troubleshooting and Diagnostics 90- 8M0182076 eng NOVEMBER 2021 © 2022 Mercury Marine Page 7B-1 7 B
Special Tools Fuel Pressure Gauge Kit 91‑881833A03 2807 Tests the fuel pump pressure; can be used to relieve fuel pressure. Fuel Component Troubleshooting and Diagnostics Anti‑siphon Valves Anti‑siphon valves can be helpful from a safety standpoint, however, they can clog with debris, may be restrictive, or have too heavy a spring. The pressure drop across these valves can create operational problems and/or powerhead damage by restricting fuel to the fuel lift pump, and the high‑pressure fuel pump. Some symptoms of restricted (lean) fuel flow, possibly caused by use of an anti‑siphon valve, are: • Severe fuel rail pressure fluctuation • Loss of fuel pump pressure • High‑speed surging • Outboard cuts out or hesitates upon acceleration • Outboard runs rough • Outboard quits and cannot be restarted • Outboard will not start • Vapor lock Anti‑siphon valves are typically installed between the fuel tank outlet and the engine fuel inlet. Use an alternative fuel supply, such as a remote tank, to determine if bad fuel or a malfunctioning anti‑siphon valve is causing the problem. If it is found that the anti‑siphon valve is the cause of the problem, replace the anti‑siphon valve with one that has a lighter spring tension, or replace it with a solenoid‑operated fuel shutoff valve. Fuel Supply Module (FSM) The fuel supply module (FSM) that contains the fuel lift pump and the high‑pressure fuel pump is energized by a 12‑volt circuit that is controlled by the fuel pump relay (FPR). When the key switch is turned to the ON position, the PCM activates the FPR to energize the FSM for approximately three seconds before the engine is started. When the PCM receives a signal from the crankshaft position sensor, the FPR is activated again, and the FSM runs continuously until the key switch is turned off. The fuel pump circuit is protected by a 20‑amp fuse. If fuel starvation is indicated, verify high‑pressure pump operation by testing the lift pump with a vacuum gauge and checking fuel pressure on one of the fuel rails. The fuel pump circuit can be activated using the CDS G3 diagnostic interface tool. Fuel Lift Pump The fuel lift pump and high‑pressure pump are on the inside of the fuel supply module. The fuel lift pump cannot be electrically tested separately from the high‑pressure pump when installed as part of the fuel supply module assembly. The fuel lift pump can be tested for operation electrically with the CDS G3 diagnostic interface tool. NOTE: This test should be completed during engine idle or light load operation. If no fuel demand exists and the FSM is filled, the lift pump will not pull fuel to create a vacuum. At engine idle, inlet vacuum may build slowly. Test the fuel system inlet vacuum as described in the following procedure. The fuel lift pump can be tested by measuring its ability to create vacuum. Create an artificial restriction in the fuel supply line to observe how much vacuum the fuel lift pump produces. The vacuum will build slowly as the engine is consuming fuel. The fuel lift pump should be capable of achieving a vacuum of 33.68 kPa (10 in. Hg) (4.91 psi). Troubleshooting and Diagnostics Page 7B-2 © 2022 Mercury Marine 90- 8M0182076 eng NOVEMBER 2021